PREPARE and bake brownie mix as directed on package for 8-inch square pan in bottom of well-greased 9-inch spring form pan.

Filling

MIX cream cheese, sugar and vanilla with electric mixer on medium speed until well blended. Blend in sour cream. Add eggs, mixing on low speed just until blended. Pour over brownie crust.

BAKE at 325 degrees F for 1 hour and 5 minutes or until center is almost set if using a shiny spring form pan. (Bake at 300 degrees F for 1 hour to 1 hour and 5 minutes or until center is almost set if using a dark nonstick spring form pan.) Run knife or metal spatula around rim of pan to loosen cake; cool before removing rim of pan. Refrigerate 4 hours or overnight.